When a shortage of refrigerant takes place in the refrigeration system of an air conditioner, not only the refrigeration system will be starved but the refrigerant compressor forming part of the refrigeration system will fail to be properly lubricated. Insufficient lubrication of the refrigerant compressor results in overheating of the compressor and further in production of unusual noises in the compressor.
To avoid these inconveniences, it has been proposed and put into practice to provide a compressor protective switch system for the refrigerant compressor in the refrigeration system of an automotive air conditioner. The compressor protective switch system is electrically connected between a power source and an electromagnetic clutch of the refrigerant compressor and is adapted to stop the supply of current to the electromagnetic clutch from the power source through detection of a shortage of the refrigerant being circulated through the refrigeration system during operation of the air conditioner.
A known compressor protective switch system for the refrigerant compressor of the refrigeration system of an automotive air conditioner uses a pressure sensitive switch adapted to detect a shortage of the refrigerant in the refrigeration system from an unusual drop in the pressure of the refrigerant being circulated through the refrigeration system. The pressure sensitive switch is thus arranged to be open in response to a refrigerant pressure which is lower than a predetermiend value.
Problems are, however, encountered in a prior-art compressor protective switch system using such a pressure sensitive switch, as will be described in detail. An object of the present invention is to provide an improved compressor protective switch system which will eliminate the problems which have thus far been encountered in a conventional compressor protective switch system of the above described nature.